Device for deburring workpieces, in particular moulded parts and castings made of plastics, rubber or the like

ABSTRACT

The invention concerns a device for deburring workpieces, in particular moulded parts and castings made of plastics, rubber or the like, said device comprising a rotatable shank ( 1 ) and linear tool elements ( 5, 6 ) which, in the axial direction, extend coaxially to the shank axis, are secured relative to the shank ( 1 ) and, as the latter rotates, can bulge out radially under the effect of centrifugal force. The device is designed such that an upper and a lower carrier ( 2, 3 ) are secured on the shank ( 1 ). The tool elements ( 5, 6 ) consist of individual threads or thread bundles whose ends are secured in the upper and lower carriers, a spring arrangement ( 7 ) being disposed concentrically with the shank ( 1 ) between the upper and lower carriers ( 2, 3 ).

This invention refers to a device for deburring workpieces, inparticular moulded parts and castings made of plastics, rubber or thelike, said device comprising a rotatable shank and linear tool elementswhich, in the axial direction, extend coaxially to the shank axis, aresecured relative to the shank, and as the latter rotates, can bulge outradially under the effect of centrifugal forces.

Deburring devices with rigid cutting edges are known by means of whichthe burrs can be removed from moulded parts. Such tools are pressedagainst the workpiece to be processed with an adjustable force. Inpractice the problem arises that the burrs can only partly be removed orthat while deburring it happens that not only the burr itself isremoved, but that the tool also cuts into the surface of the workpiece.

Moreover, rotating tools formed as deburring brushes are known thebristles of which are made from metal and are clamped in such a mannerthat in operation their shape will not or practically not change. Whendeburring parts made of plastics or rubber, there is the danger that thesurface of the workpiece also is subject to damage because the materialthe workpiece is made of is by far softer than that of the worktool sothat the worktool when acting upon the surface of the workpiece willremove material from the workpiece.

Furthermore, from DE 44 45 592 A1 rotating tools are known which use acontinuous rope of metal threads the ends of which are connected witheach other, and which in a peripheral direction or alternativelyconcentrically to the rotational axis of the tool is provided with aplurality of coaxial sections which form the outer periphery of thetool. The rotating metal portion is twisted around a support, and theindividual sections of the wire rope are fastened to the supports insuch a manner that they are flexible in radial direction so that in viewof the centrifugal force they bend or bulge outwardly when being rotatedand exert an elastic pressure against the surface of the tool. This typeof tool causes problems in practice because when treating complicatedcontours the metal rope dependent on the type of material and shape ofthe tool attacks and damages the surface of the workpiece because thelife of the tools in view of the friction of the rope against thesupports and the guide rollers for the rope are extremeley short so thatthe metal rope is to be exchanged rather often and accordingly anautomatic operation procedure is to be interrupted, and because in viewof the necessity for lubricating the support the lubricating particlescarried along by the rope are intolerable on the workpiece and are to beavoided.

It is an object of this invention to provide a rotating device accordingto the introductory part of claim 1 in such a manner that the tool isable to handle also complicated shapes of contours and burrs on thesurfaces of workpieces without any problems, that the tool is of simplestructure and that it has a long life.

According to this invention this object is solved by a device which isdesigned such that an upper and a lower carrier are secured on theshank, that the tool elements consist of individual threads or bundlesof threads, the ends of which are fastened with the upper and lowercarriers, and that a spring arrangement is provided concentrically withthe shank between the upper and the lower carriers. Such device can beoperated in connection with a motor driven manual device, f.e. adrilling machine, however, it can also be attached to a roboter head,which in a programmable manner automatically deburs the workpiece to beprocessed.

The tool elements comprising individual threads, cords or the like, orbundles thereof, preferably are filaments which are fastenedindividually or in bundles at the upper and at the lower support.Preferably the ends of the threads resp. filaments are clamped to thesupports. With a preferred embodiment of the invention the ends of thethreads resp. filaments are clamped between the support body and alid-type closure overlapping the support so that by putting the lid onunder pressure the entirety of the ends of the threads or filaments willbe fastened.

With a revised embodiment of the invention the upper and the lowersupports on their peripheral surface are provided with extensionsdirected radially outwardly, which extensions are formed in such amanner that they receive the threads or thread bundles. Said extensionscan be screw bolts screwed into the peripheral surface of the supportsend said screw bolts are provided with peripheral grooves, screw headsor the like on their outer end, which receive the threads or threadbundles. The threads can be continuously guided around the receivinggrooves as endless threads or in loops, they can be thread ringstensioned between the upper and the lower support, or the like. In orderto hold or clamp the threads or thread bundles within the supports ofthe carriers a lid-like closure each is put on top of the upper and thelower support so that the free rim of the lid is provided with elementsbeing clamped by means of the pressure of the lid onto the support, andso that the threads cannot change their position at the supports duringthe process. Said elements for example are O-ring gaskets. Also withthis embodiment a spring system is provided in order to bias thesupports against each other.

With the device according to the invention the tool elements, namelythreads and filaments, such as cords made from plastics or metalthreads, can be exchanged in an extremely simple and useful manner,because the ends of the individual threads or filaments simply need tobe clamped on and off, or are to be inserted as a unit together with theupper and lower supports and are fastened by means of the lid-type upperand lower closings. The length of the threads or filaments is chosenlonger than the distance between the upper and the lower support so thatthe threads or filaments in their central area are curved outwardly,when rotated. The extent of curvature can be adjusted according to therequirements of the practical use and dependent on the requirements ofthe deburring operation in connection with the materials of theworkpiece, or alternatively can be adjusted automatically by therotation of the tool. This is obtained by inserting spring means, suchas a coil spring between the upper and the lower support, which springmeans is formed as a pressure spring determining in the inactiveposition a maximum distance between the upper and the lower support,however, when rotating the system in view of the centrifugal force thethreads or filaments are urged outwardly in a radial direction so thatthe movable clamping means, for example at the lower support, tends toshorten the distance between the upper and the lower support andcompresses the coil spring so that the extent of the curvature isdependent on the number of rotations per time unit.

The device according to the invention operates in a very simple andeffective manner, is economical, allows an extremely smooth and carefulmachining of the workpiece, high life of the tool elements and anadaption to different deburring problems or alternatively to mouldedparts made of plastics or rubber which are to be deburred. The saiddevice is especially useful for automatic deburring processes at roboterstations. Tool and workpiece are adjustable relative to each other.

In the following the invention is described in combination with thedrawings by two embodiments.

FIG. 1 shows a schematic lateral view of an embodiment of the invention,

FIG. 2 is another embodiment of the invention in a lateral view, and

FIG. 3 is a plan view of the support according to FIG. 2.

A shank 1, which can be rotated by means of a spindle drive (not shown)is provided with an upper carrier 2 on its upper part, and a lowercarrier 3 on its lower part. The lower carrier 3 is movable in heightalong shank 1 and is restricted downwardly by a counter nut. Betweenupper carrier 2 and lower carrier 3 tool elements 5, 6, such as threads,filaments, cords or the like are stretched. The distance between the twocarriers 2 and 3 is determined by a coil spring 7 fastened on shank 1,which coil spring urges the lower carrier 3 downwardly. The threads,filements 5, 6 or the like with their upper ends 8, 9 are attached tothe upper carrier 2, the opposite ends 10, 11 either individually or inbundles are attached to the lower carrier 3. The filaments with theirends 8, 9 as well 10, 11 can be fastened to the outer periphery of thecarrier body 13 and are clamped by putting the corresponding lids 14, 16at top thereof. Spring 7 is set up onto the head 12 of the shank at themovable end and is fastened therewith. Head 12 is connected with thelower carrier 3 and both are guided together on shank 1. By changing therotational speed of shaft 1 the centrifugal force exerted onto the toolelements 5, 6 is varied. Dependent thereon the movable lower carrier 3is moved upwardly or downwardly on shank 1. This movement iscounteracted by the spring force of spring 7.

17 indicates the rotational direction of the rotating shank 1, 18 is theradial movement of the tool elements 5, 6, and 19 is the axial movementof spring 7 as well the lower carrier 3 and accordingly the bulging ofthe tool elements 5, 6.

The embodiments according to FIGS. 2 and 3 show an upper carrier 20 anda lower carrier 21 with a plurality each of projections 23, such asscrew bolts, distant from each other in a peripheral direction andextending outwardly in a radial direction beyond the carrier 20 resp. 21which screw bolts are screwed onto the corresponding carriers by meansof shanks 22. Associated to the carriers 20, 21 is a closing lid 24, 24′each, the peripheral rim 25, 25′ of which at its free end receives agasket 26, 26′, such as an O-ring, which exerts a pressure onto thethreads 5, 6 guided within projections 23 by clamping means 27, 27′.Further clamping means 28, 28′ are provided at opposite sides of thecarriers 20, 21 on shank 29. Between the two clamping means 28, 28′ apressure spring 30 is provided, which under pressure pulls apart thecarriers 20, 21 and keeps the threads 5, 6 tensioned. When rotating thedevice the centrifugal force causes the threads 5, 6 to bulge (as shownin FIG. 1), and accordingly results in a relative movement of the onecarrier against the other, whereby at the same time the pressure spring30 is compressed.

Threads 5, 6 can be positioned within grooves of the projections 23.They can pass continuously from an upper projection to a lowerprojection (individually or in bundles), then towards the next upperprojection in peripheral direction and so forth, or merely between upperand lower associated projections each, or can be wound in any otherscheme.

What is claimed is:
 1. Device for deburring workpieces comprising arotatable shank having a longitudinal axis, an upper and a lowercarriage secured on the shank, linear tool elements consisting offilaments, the ends of the filaments being secured in the upper and thelower carrier, and a spring arrangement disposed concentrically with theshank between the upper and the lower carrier, characterized in that thefilaments extend coaxially to the longitudinal axis of the shank and thefilaments bulge out radially under the effect of centrifugal force asthe shank rotates, wherein the extent of the bulging of the filaments isdependent on the number of rotations per time unit, wherein one of theupper and the lower carrier is provided with a counter nut which isadjustably connected with the shank, and which determines the maximumdistance between the upper and the lower carrier.
 2. Device according toclaim 1, wherein the ends of the filaments are clamped at the carriers.3. Device according to claim 2, wherein the carriers each comprise acarrier body and a lid-type end portion overlapping the carrier body,and the ends of the filaments are clamped between the carrier body andthe lid-type end portion.
 4. Device according to claim 1, wherein theupper and the lower carrier are provided with extensions directedradially outwardly to their peripheral surfaces and designed forreceiving the ends of the filaments.
 5. Device for deburring workpiecescomprising a rotatable shank having a longitudinal axis, an upper and alower carriage secured on the shank, linear tool elements consisting offilaments, the ends of the filaments being secured in the upper and thelower carrier, and a spring arrangement disposed concentrically with theshank between the upper and the lower carrier, characterized in that thefilaments extend coaxially to the longitudinal axis of the shank and thefilaments bulge out radially under the effect of centrifugal force asthe shank rotates, wherein the extent of the bulging of the filaments isdependent on the number of rotations per time unit, wherein the upperand the lower carrier are provided with extensions which are directedradially outwardly to their peripheral surfaces and are designed forreceiving the ends of the filaments, wherein the extensions are screwbolts screwed into bores of the peripheral surface of the carriers whichscrew bolts are provided with means for retaining the filaments. 6.Device for deburring workpieces comprising a rotatable shank having alongitudinal axis, an upper and a lower carriage secured on the shank,linear tool elements consisting of filaments, the ends of the filamentsbeing secured in the upper and the lower carrier, and a springarrangement disposed concentrically with the shank between the upper andthe lower carrier, characterized in that the filaments extend coaxiallyto the longitudinal axis of the shank and the filaments bulge outradially under the effect of centrifugal force as the shank rotates,wherein the extent of the bulging of the filaments is dependent on thenumber of rotations per time unit, the upper and the lower carrier areprovided with extensions which are directed radially outwardly to theirperipheral surfaces and are designed for receiving the ends of thefilaments, wherein the filaments are secured by grooves or screw heads.7. Device according to claim 6, wherein at the lower and the upper areaof the shank a lid-type cover is provided having a ring gasket at thefree peripheral end arranged so that said gasket under pressure restsupon the filaments wound around the means, and fixes the filaments inoperation.
 8. Device according to claim 7, wherein the ring gasket is anO-ring gasket.
 9. Device according to claim 8, wherein the upper and thelower lid-type covers are fastened by counter nuts, so that the O-ringsare pressed against the filaments.
 10. Device for deburring workpiecescomprising a rotatable shank having a longitudinal axis, an upper and alower carriage secured on the shank, linear tool elements consisting offilaments, the ends of the filaments being secured in the upper and thelower carrier, and a spring arrangement disposed concentrically with theshank between the upper and the lower carrier, characterized in that thefilaments extend coaxially to the longitudinal axis of the shank and thefilaments bulge out radially under the effect of centrifugal force asthe shank rotates, wherein the extent of the bulging of the filaments isdependent on the number of rotations per time unit, the upper and thelower carrier are provided with extensions which are directed radiallyoutwardly to their peripheral surfaces and are designed for receivingthe ends of the filaments, wherein at least one of the carriers isattached movably in height on said shank, and is restricted by counternuts and an adjusting screw outwardly on the shank.